"In a DBA?"
As noted, an IRA is an account owned by an individual. The concept of "doing business as" simply has no application here. I have no idea what your customer is trying to accomplish and seriously doubt that he does either.
The account should be titled in the name of the individual with no other verbiage other than that indicating it is an IRA, and, perhaps, that your bank holds it as a fiduciary.
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In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.